When data is presented pictorially, our well developed two and three dimensionally oriented eye-brain pattern recognition mechanism allows us to perceive and process many types of data very rapidly and efficiently. In fact, in many implementation, design, and construction processes, pictures are virtually indispensable for visualizing and communicating.
However, creating and reproducing a meaningful picture presents problems that have stood in the way of widespread use of pictures. The ancient Chinese proverb "a picture is worth a thousand words" only became a cliche in our society after the introduction of technological means (the printing press and later photography) of producing and reproducing pictures easily and cheaply.
These technology breakthroughs made it fast and easy to capture the essence of an idea or situation with an illustrative drawing or photograph. No longer was it necessary to painstakingly draw, carve, or paint individual copies of a scene.
Today, the blending and enhancing of the inter-relationship of computer graphics and video are the most important mechanized means of producing and reproducing pictures since the invention of the television.
Video provides us with the opportunity to review events which have already occurred and to witness events, which we otherwise could not attend, as they unfold. Graphics, on the other hand, with the assistance of a computer, provides the advantage of enabling us to create and perceive pictures of abstract, synthetic objects, including graphs and charts. Lastly, interactive graphics, which is a form of human-machine interaction, combines the best features of the interactiveness of textural communication with the graphical communication of two and three dimensional plotting.
Arguably, static pictures were often a good means of communicating information, dynamically varying pictures are frequently even better. This is especially true when one needs individualized time varying phenomena, both real (e.g., deflection of an aircraft wing in supersonic flight, or the evolution of a human face from childhood through old age) and abstract (e.g., growth trends such as the use of nuclear energy in the USA or the population movement from cities to suburbs and back to the cities, as functions of time).
A movie is therefore often more expressive in showing changes over time than, say, a sequence of slides. Similarly, a dynamic sequence of frames on a display console can often convey smooth motion or changing form better than a slowly changing sequence of individual frames. This is especially true when the user can control the animation by adjusting its speed, the proportion of the total scene and the amount of detail shown, and other effects. In a video format, adjustments are made by reversing the image, scaling and zooming, as well as other video manipulations. Much of the technology for the mixing of video and graphics therefore deals with a combination of hardware and software techniques.
Thus, the mixing of video and graphics allows us to achieve much higher bandwidth human-machine communication using a judicious combination of text with static and dynamic pictures than is possible with text alone. This higher bandwidth makes a significant difference in our ability to understand data, perceive trends, and visualize real or imaginary objects. By making communication more efficient, mixing technology makes possible greater productivity, higher quality and more precise results or products, and lower analysis and design costs.
Traditionally, video and graphics data, which are in digital format, are stored within two frame buffers, or memory storage areas. The graphics data is stored in one memory area, while the video data is stored in another memory area. Both sets of data are accessed and converted to an analog signal. These analog signals are then mixed, on a pixel by pixel basis, and sent to a display station.
This method of mixing video and graphics data is referred to as a "video overlay," i.e., the video data is overlaid on top of the graphics data. There are three traditional methods for accomplishing this.
One method teaches that within the graphics environment, a particular color is defined to be an overlay color. In other words, by designating a particular color as the overlay or transparent color, the implementation of the method treats all instances of that color as transparent, i.e., wherever that color appears within the graphics data, video data will be seen to show through. This method of mixing video with graphics is well-known as the "Overlay Key Color Method." A second method of mixing video data with graphics data is to actually create a rectangular window, and utilize the window to create a window-within-a-window image. This method is now available in many television sets, as the "picture-within-the-picture," the difference being that in such an implementation two video signals are being mixed, as opposed to video and graphics signals. With this method, the graphics data provides the background, while the video data is mapped to the rectangular window area. This creates the appearance that the video data is on top of the graphics data. This is known as the "X-Y Window" method of mixing video and graphics data.
The last method utilizes a system for "tagging" a stream of video data. The video data is evaluated and a search is conducted for a particular color or range of colors, each piece of data having such a range is then chroma key color tagged. Later, when the video is mixed with the graphics data, the video is projected on top of the graphics, and each chroma-key color tagged piece of data is treated as either opaque or transparent. The piece of data which was not tagged is therefore treated in a complemented manner. This is known as the "Video Chroma Key Tag" method of mixing video and graphics data.
Each of the three above methods is hardware dependent. As such, only one method may be implemented within one computer at a particular time. This limits the user to that specific implementation.
Thus, a user wishing to implement the Video Chroma Key Tag Method on a computer in which one of the other two methods exists is required to physically remove the hardware supporting the present method and insert the Video Chroma Key Tag hardware in its place.
Accordingly, there exists a need in the art for a means by which to switch dynamically among the various graphics and video mixing methods which is both efficient and accurate.
There exists a further need in the art for a means by which to switch among the various graphics and video mixing methods which is hardware independent.
There exists still a further need in the art for a means by which to switch among the various graphics and video mixing methods which can operate in real-time.
There exists still a further need in the art for a means by which to utilize the various graphics and video mixing methods such that they interact and cooperate with each other to coexist simultaneously upon a single display device.